Bill Gates' nuclear firm plans hot, salty push into power

The nuclear power firm being hailed by Bill Gates as the answer to mankind's future energy needs is planning a proprietary approach to an old atomic idea to further its global ambitions.

TerraPower is an offshoot of patent holding company Intellectual Ventures, which was co-founded by former 14-year Microsoftie Nathan Myhrvold. It was showcased by Bill Gates at TED in 2010 and the main area the firm is working on is a traveling-wave reactor (TWR).

A TWR mostly burns depleted uranium fuel, which is stacked in a long candle-like column and then ignited with a cap of enriched uranium. Such a fission reactor would take 50-100 years to burn itself down, with virtually no maintenance required or spent fuel to dispose of, and proposed power plants could produce 300MWe and 1,000MWe cheaply and simply.

In an interview with the Weinberg Foundation, TerraPower's CEO John Gilleland said that the firm was on schedule to build a 600MW test-bed reactor by 2022, and to get its first full-power system up and running a few years later.

But the design for the TWR has changed slightly with further research, Gilleland said, and the plan now is to trigger the wave of fission in the center of the column and harvest the heat that can be used for power generation there.

"It's basically the same physics of what we started out with," he said. "It's just the practical considerations associated with making the most use of every neutron, and the engineers' love of keeping the cooling system in one place, and not chasing the wave. It didn't set us back at all."

Patented power

But TWR isn't the only trick up TerraPower's sleeve, Gilleland said. The company is also working on a proprietary type of molten-salt nuclear reactor (MSR), thanks to new research into making the original 1950s design more efficient.

Like TWR, this type of fission reactor uses nuclear fuel considered "waste" today, but dissolves it in salts which are passed through a graphite core to generate heat. It's safer than current designs because the system isn't pressurized and if power at the plant fails (as at Fukushima), the system automatically shuts itself down.

An MIT startup is planning a 500MWe test reactor along these lines called the Waste Annihilating Molten Salt Reactor (WAMSR) which would cost $1.5bn. Using reactors of this type would produce enough power to meet the world's needs for the next 70 years using currently available nuclear waste stocks, it claims.

But Gilleland explained that there were issues with many MSR designs as they stand. The firm is looking to adapt the designs of the Oak Ridge MSR, which ran continuously from 1965 to 1969 with no problems, and said TerraPower researchers are "having fun" with the plans, but that no patents have been filed yet.

"We're thinking about it and trying to work on it and we have a few proprietary ideas that we're cooking up," he said. "We like to work on an idea for a while before we run out and tell about it – so we have some ideas which we're trying to ferret out how good they are."

Forget fusion

One area the firm won't be seriously looking into is fusion power. This might seem odd, since Gilleland was the US managing director of the International Thermonuclear Experimental Reactor (ITER) fusion plant, based in France, before joining TerraPower, but he said that the payoff period for research is too long.

"I have a soft spot in my heart for fusion, having run the ITER program and things like that, but it's something I can't count on for my grandchildren," he said. "We're focused more on fission rather than fusion. Fusion just takes so much more development and so much more time."

Nevertheless, no ideas are off the table he said. TerraPower has set up an engineering "skunk works" to encourage creative and lateral thought among staff. This involves giving them a lot of freedom to noodle around with new ideas.

"It's like Google and other places – the best ideas sometimes came from the person doing the backstroke in the swimming pool, or at home thinking. So we want to just make sure that people have a certain fraction of their time for free thinking." ®